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Fixed 8-bit dram (framebuffer) access for 32x [David Haywood]

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This commit is contained in:
Angelo Salese 2010-09-27 02:22:40 +00:00
parent 21aa2c8cf4
commit 959aafaf6a
1 changed files with 26 additions and 1 deletions
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27
src/mame/drivers/megadriv.c
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@ -2314,7 +2314,32 @@ static READ16_HANDLER( _32x_68k_dram_r )
static WRITE16_HANDLER( _32x_68k_dram_w )
{
COMBINE_DATA(&_32x_access_dram[offset]);
if ((mem_mask&0xffff) == 0xffff)
{
// 16-bit accesses are normal
COMBINE_DATA(&_32x_access_dram[offset]);
}
else
{
// 8-bit writes act as if they were going to the overwrite region!
// bc-racers and world series baseball rely on this!
// (tested on real hw)
if ((mem_mask & 0xffff) == 0xff00)
{
if ((data & 0xff00) != 0x0000)
{
_32x_access_dram[offset] = (data & 0xff00) | (_32x_access_dram[offset] & 0x00ff);
}
}
else if ((mem_mask & 0xffff) == 0x00ff)
{
if ((data & 0x00ff) != 0x0000)
{
_32x_access_dram[offset] = (data & 0x00ff) | (_32x_access_dram[offset] & 0xff00);
}
}
}
}
static READ16_HANDLER( _32x_68k_dram_overwrite_r )